1. Field of the Invention
The present invention relates to a new and improved joint for attaching adjacently disposed missile sections together. More specifically, the present invention relates to a unique flange joint assembly adaptable for joining the cylindrical casing of a recycled rocket motor section to an adjacent section by utilizing a number of unique attachment blocks mounted on the rocket casing and bolted to the adjacent missile section.
2. Description of the Related Art
In an effort to contain missile manufacturing costs while maintaining the required level of performance and quality, it would be useful to be able to recycle certain existing missile components. For example, in manufacturing the AIM-9X tactical missile, it would be highly desirable to utilize existing rocket motor assemblies along side newly manufactured control actuator section (CAS).
Typically, when manufacturing an entirely new missile assembly, adjacent sections are attached to one another by a series of conventional fasteners such as radial screws or bolts. The machining process for creating the tight tolerance countersunk through holes in the rocket motor housing necessary to receive the screws or bolts requires drilling a large number of holes having relatively high tolerances. Relaxing the tolerances could lead to larger hole clearances, creating xe2x80x9cloose jointsxe2x80x9d. Because a newly manufactured rocket assembly has not yet been filled with xe2x80x9clive propellant,xe2x80x9d the manufacturing process is not considered to be dangerous.
However, when recycling existing rocket motor assemblies, certain factors need be considered. In particular, the need for a large number of conventional radial screw holes to achieve rigid attachment can be a dangerous undertaking when the rocket housing contains xe2x80x9clive propellant.xe2x80x9d In addition, conventional radial screw joints have been found lacking in both strength and stiffness. If the tolerances for the radial screw joints are not maintained, joint failure could occur during missile operation. Finally, it has proven difficult to properly seal such radial screw joints.
It is clear that there exists a need in the art for a universal joint assembly that can be utilized when attaching adjacent missile sections together. The joint should be easy to assemble, provide the strongest possible attachment while ensuring that attached missile sections remain in abutment during flight of the missile. Such a universal joint should avoid the need for relatively high tolerances and should be capable of easy sealing. As will become apparent, the present invention meets all of these requirements in a unique and efficient universal joint assembly.
This need in the art for utilizing recycling existing rocket motors when manufacturing new missiles assemblies is possible because of the unique, universal joint assembly of the present invention. The universal joint of the present invention includes a plurality of separate attachment blocks. To prevent disruption of the stream of air flowing past the missile during flight operation, the attachment blocks may be aligned with existing fairings extending axially along the surface of the missile. The AIM-9X, for example, has four such external fairings and would therefore utilize four (4) attachment blocks when joining a recycled rocket motor an adjacent CAS. When four fairings are present, the fairings and the four attachment blocks are positioned about the missile circumference at approximately 90xc2x0 intervals to one another.
Each attachment block has blind bore holes aligned with through holes extending completely through the outer casing of the rocket motor. Bolts or screws extending through the rocket casing and into the attachment blocks may be selectively adjusted to tighten the attachment blocks to the casing outer surface. When mounted on the rocket casing, the attachment blocks function in a manner similar to flanges. Because the rocket motor casing is joined only to the attachment blocks, the holes machined in the rocket casing do not require the higher tolerances necessary were the rocket casing to be screwed or bolted directly to the CAS.
Additional holes are machined in a substantially axial direction completely through each attachment block. The additional holes are aligned with blind bore holes machined in the end face of the CAS. When assembled, axial screws extend though the attachment block and into blind bore holes. As the axial screws are tightened, they pull the attachment blocks and connected rocket motor casing toward the CAS until the aft face of the rocket casing abuts the flat forward face of the CAS. The attachment blocks are formed such that as the cylindrical surfaces of the rocket casing and CAS make surface contact, none of the attachment blocks contacts the CAS.
Each attachment block replaces only a portion of a fairing extending along the outer surface of the rocket casing. The attachment blocks are specifically designed to have no aerodynamic envelope impact. Preferably, the attachment blocks are positioned onto an aft section of the rocket motor casing at a location between the ortman key slot and the aft end of the casing.
While the present invention employs four attachment blocks for use in manufacturing an AIM-9X missile including four fairings, it is within the scope of the present invention to have any number of such attachment blocks depending only on the number of fairings/fins extending along the outer surface of the missile. Likewise, while the preferred embodiment employs two screws or bolts to join each attachment block to the CAS and two additional screws or bolts to mount each attachment block on the rocket casing, any number of screws, bolts or other fasteners may be employed depending on the size of the missile and attachment blocks.